Existing projection systems irradiate light emitted from various light sources onto various wavelength conversion devices to generate excited light of different colors, such as red excited light, green excited light and blue excited light, which is then combined into white light to display projection images.
As shown in FIG. 1, an existing projection system comprises laser modules 31, 32 and 33 for emitting blue light; a wavelength conversion device 11 including green/yellow phosphor, a wavelength conversion device 12 including red/yellow phosphor, a diffusing color wheel 13, condenser lenses 21 and 22 respectively corresponding to the wavelength conversion devices 11 and 12 for converging collimated light, a filter 41 for transmitting blue light while reflecting other light, a filter 42 for transmitting blue light while reflecting red light, a filter 40 for transmitting red light while reflecting other light, and a filter 43 for reflecting blue light while transmitting other light.
In particular, after passing through the filter 41 and the condenser lens 21, the blue light emitted from the laser module 31 is incident onto the wavelength conversion device 11 to generate green light. Then, the green light is incident onto the filter 43 after being reflected by the filter 41 and the filter 40. After passing through the filter 42 and the condenser lens 22, the blue light emitted from the laser module 32 is incident onto the wavelength conversion device 12 to generate red light. Then the red light is incident onto the filter 43 after being reflected by the filter 42 and the filter 40. After being diffused by the diffusing color wheel 13, the blue light emitted from the laser module 33 is incident onto the filter 43. Then the green light and red light transmitted by the filter 43, and the blue light reflected by the filter 43 are combined into white light for displaying projection images.
However, because the projection system relies on different light sources to generate different excited light, and different filters to filter or combine different excited light, the size of the projection system is bulky and the cost of the projection system is high.